A wavelength is the distance sound will travel while one cycle of
the sound occurs. The speed of sound varies a little depending on air pressure,
temperature, and humidity, so the speed of sound is different at sea level than it might
be in the mountains. That also means the wavelengths will be longer or shorter depending
on the air pressure. The speed of sound is a very important variable when calculating
wavelengths of sounds. For instance if your listening to a bass note that's 40Hz, that
means there are 40 cycles per second, if the speed of sound where we are is 1127 feet per
second then we can figure out that each wavelength is 28.18 feet long. We do this by
dividing the speed of sound by the frequency, in this case 1127/40=28.18... I like
to do these calculations in a computer spread sheet so I can easily change the speed of
sound or the frequency and do many calculations quickly.

The following chart was done with a spreadsheet and can be a handy
reference. The speed of sound is assumed to be 1127fps for the following calculations, the
lengths are feet.

Freq

Length

1/2 length

1/4 Length

20

56.35

28.18

14.09

40

28.18

14.09

7.04

50

22.54

11.27

5.64

60

18.78

9.39

4.70

80

14.09

7.04

3.52

90

12.52

6.26

3.13

100

11.27

5.64

2.82

120

9.39

4.70

2.35

150

7.51

3.76

1.88

180

6.26

3.13

1.57

190

5.93

2.97

1.48

200

5.64

2.82

1.41

210

5.37

2.68

1.34

220

5.12

2.56

1.28

230

4.90

2.45

1.23

250

4.51

2.25

1.13

280

4.03

2.01

1.01

300

3.76

1.88

0.94

350

3.22

1.61

0.81

400

2.82

1.41

0.70

500

2.25

1.13

0.56

1000

1.13

0.56

0.28

2000

0.56

0.28

0.14

5000

0.23

0.11

0.06

8000

0.14

0.07

0.04

10000

0.11

0.06

0.03

14000

0.08

0.04

0.02

15000

0.08

0.04

0.02

18000

0.06

0.03

0.02

20000

0.06

0.03

0.01

Notice the low frequencies wavelengths are much longer than the
high frequencies, with 20Hz being 56 feet long where as 20kHz is only 6 hundredths of a
foot! (that's a little more than half an inch)...

Now the fun stuff comes when we start comparing mounting locations
to wavelengths!

We all know if we mount two speakers near each other they will
reinforce each other and make more sound than one! We also know that if we accidentally
hook up a speaker backwards it will interfere with the other woofers because they are out
of phase, cancellation will occur. The same cancellation will occur if we receive sounds
from speakers that differ by 1/2 wavelength. If we mount speakers 1/2 wavelength apart the
sound from one will cancel when it reaches the other. The good news is, in a car the
distances are short and most bass sounds are constantly reinforcing each other. But when
you get to the mids and highs of a system there is no way to keep the wavelengths nearly
equal, cancellation at certain frequencies can cause big problems, and is a major pain to
people seeking true audiophile reproduction

Use the chart above to help make sense of your speaker mounting
locations.

Wavelength of Radio Wavesby: Andrew Krause

The method for finding wavelength with radio is a bit different.
To find radio wave lenghts, divide the frequency in megahertz into 300. This is
useful for determining antenna sizes, or just because you want to know.

Lambda, or the greek letter "l" is used to represent wavelength in formulas such as the one below.